This topic describes the limits of EventBridge. To prevent application exceptions, do not exceed the limits when you use EventBridge.

The following table describes the limits of EventBridge.

Category Item Description
Event bus Total number of system event buses A maximum of one system event bus is allowed.
Total number of custom event buses A maximum of 10 custom event buses are allowed.
Number of event rules for an event bus A maximum of 10 event rules are allowed for an event bus.
Name of an event bus
  • The name can be up to 127 characters in length. It must start with a letter or a digit, and can contain letters, digits, and hyphens (-).
  • The reserved keyword "default" cannot be used as the name of an event bus.
  • The name cannot be a string that is prefixed by eventbridge-reserved-.
Frequency of calling the PutEvents operation A maximum of 3,000 queries per second (QPS) are allowed.
Event rule Event target of an event rule
  • A maximum of five event targets are allowed.
  • An event target must reside in the same region as EventBridge.
  • An event target must be a service instance owned by your Alibaba Cloud account.
  • The ID of an event target must be unique.
Pattern of an event rule Each field in the stringExpression pattern can contain up to five expressions in the map data structure.
Name of an event rule
  • The name can be up to 127 characters in length. It must start with a letter or a digit, and can contain letters, digits, and hyphens (-).
  • The name cannot be a string that is prefixed by eventbridge-reserved-.
Transformation of the event content
  • A template can be up to 10,240 characters in length.

  • A value can be up to 1,024 characters in length.

Event Event message
  • The maximum size of a single event message is 64 KB.
  • A maximum of 16 event messages can be sent at a time.
  • The maximum size of event messages that are sent at a time is 256 KB.
Event parameters
  • id: The value can be up to 128 characters in length. It must start with a letter or a digit, and can contain letters, digits, and hyphens (-).
  • source: The value can be up to 128 characters in length.
  • subject: The value can be up to 512 characters in length.
  • type: The value can be up to 64 characters in length.
Schema Schema name
  • The name can contain only letters, digits, hyphens (-), underscores (_), and periods (.).
  • The name can be up to 128 characters in length. If the name that you specify is more than 128 characters in length, excess characters are deleted.
Schema version A maximum of 1,000 schema versions are allowed.